1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method, and to a storing medium, and more particularly to an image processing apparatus and method suitable for application to a digital copier, a scanner or the like, and to a storing medium.
2. Related Background Art
An image processing apparatus such as a digital copier and a scanner is known, which reads an image of an original placed on an original support and executes predetermined image processing. In a conventional image processing apparatus, a timing signal is generated in accordance with a clock signal having a fixed frequency generated by a clock signal generation unit such as a quartz oscillator, and synchronously with this timing signal, an original image is read to generate image data which is subjected to various image processing.
With recent high speed and high resolution of sophisticated image processing techniques, the frequency of a clock signal to be used for the image processing by an image processing apparatus is becoming high. On the other hands, regulations on noises radiated from various electronic apparatuses are becoming sever one year after another. If the clock frequency is raised as in recent years, it is predicted that countermeasures against radiation noises of an image processing apparatus become more difficult. In order to meet the specifications of electromagnetic interference (EMI) adopted worldwide, it is necessary to suppress the amount of radiation noises, which results in a smaller degree of design freedom, a larger load upon a designer and a technical person, and a rise of manufacture cost.
As countermeasures against such radiation noises, there is a method of modulating the frequency of a clock signal. However, if image data is processed by using a timing signal generated in accordance with a frequency-modulated clock signal, there occurs a problem that when the processed image data is output on a recording apparatus such as a printer, the size of each dot becomes different. Furthermore, an abnormal operation, if any, of a frequency modulation function cannot be notified to a user.